The invention relates to an installation for signalling the deceleration of a motor vehicle, comprising a signal lamp having an illuminating area which lights up in the event of deceleration of the vehicle, this illuminating area being divided into lighting sections, each section being equipped with its own light source, and means for controlling the lighting of a number of light sources which increases with the deceleration of the vehicle so as to obtain a lit surface of the illuminating area representative of this deceleration.
The stop lamps placed at the rear of a vehicle light up when the brake pedal is actuated. They thus allow the driver of a following vehicle to anticipate a slowing-down and to react to it. In contrast, these lamps give no information on the strength of the braking. For this reason stop lamps have been envisaged (DE 195 06 621), particularly complementary lamps, the illuminating area of which is divided into a certain number of sections. The greater the deceleration of the vehicle, the higher the number of sections lit up. The surface of the illuminating area increases in size as a function of the deceleration and thus supplies an indication representative thereof. This allows the driver of a following vehicle to be informed as to the strength of the braking.
However, in a known lamp of this type, each section of the illuminating area emits a luminous flux of constant intensity. The overall intensity of the lamp is thus equal to the arithmetic sum of the intensities of each of the sections, such that it varies very greatly. It is a minimum when only one section is lit and a maximum when all the sections are. However, the luminous intensity of the lamp should not exceed a maximum value fixed by the regulations. If this value is not exceeded when all the sections are lit, the lamp will be difficult to discern when only one single section is lit since its luminous intensity will be weak. If the luminous intensity of a single section is sufficient to be discerned clearly, the amplitude of the variation of the signal, proportional to the total number of sections of the lamp, will have to be low so that the intensity of the lamp does not exceed the maximum value when all the sections are lit. Hence the known lamps do not make it possible fully to transmit a signal representative of the deceleration, which has the outcome either of late braking by the following vehicle, or of over-braking followed by acceleration.